My truck won't crank up

[BrandonS32]

im brand new to the forum and i have a question, i have a 1990 ford ranger and it will turn over but it will not crank up. The fuel pump is not turning on when I turn the key on, but if I jump the relay it will. Also it will crank up on starter fluid. So it has fire. Does anybody know what could be wrong?

 

[Mark_88]

Sounds like it's dead...I will buy it off you now...j/k

If it fires with starter fluid then my first guess would be a fuel problem. And the pumps not starting with the key on sounds like part of it, although that depends somewhat on how quickly you turn it on/off.

There should be a pressure regulator on the fuel rail with a vac line on it. Pull the vac line off and sniff the end of it...if you smell gas, then the regulator is shot. if not...could be something with the fuel pump. You would need to test the fuel pressure but I couldn't begin to tell you how to do that on a FI system so one of our more experienced members will have to chime in to bail you after that.

Or you could use the search feature near the top...search on "won't start" or "fuel pressure testing"...If you don't already have one you might invest in a vacuum tester as they can also test fuel pressure.

 

[BrandonS32]

Thanks for helping maybe this little bit more info will help. The fuel pump will run when I jump the 30 and 87 slots on the relay harness so I know it's not the physical fuel pump. I have tried to crank it when jumping the fuel pump, and it still won't crank do I also believe that the injectors are not firing, I have checked the solenoids on the injectors with a multimeter and they all read around 16ohms so they seem to still be good.

 

[Mark_88]

If jumping the relay gets the pump going then your relay is probably toast. However, when jumping the relay and the pump is running, does the truck actually start?

 

[BrandonS32]

I've actually replaced the relay because I thought that was the problem and I've also tried to wire up a universal relay and neither of them made a diffrence and no the truck will not crank with the fuel pump jumped

 

[alwaysFlOoReD]

If you don't already have one you might invest in a vacuum tester as they can also test fuel pressure.

While this is true it is only true for pressures related to carbs. The FI pressure is much higher than this tester will go to. Carb ~ 5 - 7 psi, FI ~ 40 psi [RBV's].
.....Unless the tester has changed, it's been a while.
Thread jack over,

Richard

 

[alwaysFlOoReD]

I'm not too good with electrical, why won't it crank when the fuel pump relay is jumped?

Richard

 

[BrandonS32]

I think the injectors are not working. My thoughts are that the is nothing wrong with the fuel pump or the injectors I think either a sensor or something in the computer is telling them not to cut on, I've been told that it may be the crankshaft position sensor but normally that would cut off the fuel and ignition. But I still have ignition.

 

[Mark_88]

While this is true it is only true for pressures related to carbs. The FI pressure is much higher than this tester will go to. Carb ~ 5 - 7 psi, FI ~ 40 psi [RBV's].
.....Unless the tester has changed, it's been a while.
Thread jack over,

Richard

Good point...mine goes above 20 psi but it's been a while since I even looked at it...could go to 50 though...

Is there a better way to test fuel pressure on FI?

I think the injectors are not working. My thoughts are that the is nothing wrong with the fuel pump or the injectors I think either a sensor or something in the computer is telling them not to cut on, I've been told that it may be the crankshaft position sensor but normally that would cut off the fuel and ignition. But I still have ignition.

Maybe inertia switch??? that kills the pump only...you can crank it till the sun goes down and it will not start.

 

[BrandonS32]

I meant to add that I have already checked that and it is fine

 

[alwaysFlOoReD]

Is there a better way to test fuel pressure on FI?

I don't know if better... I have a tester that is sorta like a compression tester. It hooks onto the schrader valve of the fuel rail of FI engines. Some auto parts stores will lend one to you with a security deposit.

Richard

 

[scheff]

im not sure if this helps or not but my truck was doing this last weak this eaxct problem. what i did was got to the fuel pump and cheaked the wire harnes that goes to it. mine was destroyed i replaced it and the truck works fine now

 

[BrandonS32]

im not sure if this helps or not but my truck was doing this last weak this eaxct problem. what i did was got to the fuel pump and cheaked the wire harnes that goes to it. mine was destroyed i replaced it and the truck works fine now

That was one of my thoughts so I took the bed off and it is fine

 

[BrandonS32]

Well I wanted to see if I could pull codes on the truck, and when I first turned the key to the on position the check engine light did not turn on for that few seconds like it should, so I figured with such an older truck somebody had removed the bulb so that the light wouldn't stay on but when I pulled the dash the bulb was there but it was blown so I took the bulb from the rear antilock light which I knew was a good bulb and when I turned the key to the on position it was still not lighting up like it should so I checked the the cigarette lighter fuse and it was good so finally I concluded that the computer has problems and I have one on order so hopefully this will fix my problems

 

[BrandonS32]

The new computer didnt work but luckily I was able to return it. Im just saying screw it I'm gutting it and getting it ready for the 302 swap. This isnt my daily driver so it doesnt really bother me, also only paying $400 for it eases the pain!